1. Field of the Invention
This invention relates to a device and method for administering a quantity of fluid to a wound site nerve bundle, or the blood stream of a patient. More specifically, this invention relates to an improved device and method for the activation of a supplemental large volume, flow-controlled bolus dose of fluid by itself or during a continuous primary infusion of fluid.
2. Description of Related Art
In instances of severe pain, infection, and other medical ailments, it has been proven beneficial to administer a continuous flow of medicinal fluid to a patient. There are many types of medicinal fluids that can be administered in this manner including, but not limited to, insulin, analgesics and antibiotics. In some instances, it is beneficial to administer a supplemental bolus dose of the medicinal fluid to a patient who is also receiving a continuous primary flow of the fluid.
The continuous delivery of such medicinal fluids over extended periods of time has required prolonged hospital stays and monitoring by medical staff. The possibility of reducing hospital stays has prompted research and development in the area of self-administration of such fluids by patients. As a result, there are several patient controlled administrative devices, (“PCA devices”) on the market. Certain PCAs enable patients to self-administer continuous as well as bolus doses of medicinal fluids. Some of these PCAs are fairly mobile and provide for a continuous or basal rate of fluid, which is the on-going continuous primary flow rate of fluid to a patient. Some PCAs also permit a supplemental or bolus dose of fluid to be administered.
However, there are dangers associated with the self-administration of certain medicinal fluids. Patients may not properly control the amount of fluid they receive and the time period during which they receive it. In particular, over-administration of analgesics, for example, may result in nausea, bowel, urinary and motor dysfunction, and even death. Many of the PCAs already on the market only provide for an on-demand rush of the medicinal fluids, whereby patients are expected to remember to turn off the bolus flow of fluid. The possibility of human error increases the risk of patient over-administration. Therefore, recent activity has been directed toward developing mobile PCAs which control both the rate of the continuous fluid and the amount of the bolus dose fluid which a patient may self-administer.
One such prior art PCA device as disclosed in U.S. Pat. No. 5,011,477 (the “Baxter device”). One major problem with this invention is that the bolus reservoir is severely inadequate for the administration of large volume bolus doses of medicinal fluid. Certain medicinal fluids, such as antibiotics, or low concentration analgesics require large volume bolus doses, such as 2–10 cc's or more of fluid per dose. Such large bolus requirements exceed the bolus dose capacity provided for in the Baxter device. It has been shown that 10 cc bolus sizes are very efficacious in wound site and nerve block procedures. New pain protocols emphasize lower concentrations and higher flow rate and larger bolus sizes. While overall dosages of medication are similar to high concentration, low flow rate protocols, the new method is preferred as safer. As a result, the bolus size requirements have been increasing. Baxter's 0.5 cc bolus device is not adequate when used with low concentrations.
The Baxter device and some other prior art PCAs require manual squeezing or pushing to release the bolus dose. A major problem with such manual squeezing or pushing is that the manual force required to administer the bolus dose is a direct function of the size of the bolus reservoir volume. The higher the bolus volume, the more squeezing or pushing force is required to release the bolus dose. Weak patients may not have the strength to self-administer large volume bolus doses in this manner.
Prior art PCAs do not control the release rate of the bolus dose to the patient or are not equipped to efficiently control the release rate of a large volume bolus of fluid. It is important to control the release rate of a bolus dose of fluid because there is a risk of injury or complication from the quick release of bolus doses and bolus doses of certain medicinal fluids should not be released into the patient all at once, but over a specified period of time. This risk increases with the size of the bolus dose required.
One prior art device, such as that disclosed in U.S. Pat. No. 6,045,533 attempts to control the release rate of the bolus dose to the patient through the use of a rotating drive wheel. However, one significant drawback of this device is that a patient cannot be expected to manually rotate a drive wheel continuously for a period of 5 minutes, which is approximately the amount of time during which a large volume bolus dose of about 10 cc's should be administered.
What is thus needed is a mobile device and method to provide a continuous and substantially constant flow of medicinal fluid and which provides a controlled, large volume supplemental bolus dose of medicinal fluid whereby the patient need not be relied upon to manually control the release rate of the large volume bolus dose. Further, an improved activation device and method is needed such that even a weak patient may administer a large bolus dose.